Problem: Simplify the following expression: ${8a+7(-5a+7)}$
Explanation: Distribute the ${7}$ into the parentheses: $ 8a + {7(}\gray{-5a+7}{)} $ $ 8a {-35a+49} $ Combine the $a$ terms: $ {8a - 35a} + 49$ $ {-27a} + 49$ The simplified expression is $-27a+49$